This blog post starts where I left off last time (with another pun!) and details my efforts on the Thomson-Walker medical print collection thus far, describing the first phase of the project.
After I had spent a few days surveying the boxes of prints I began to get a better idea of how to best approach treating the entire collection and started to investigate various rehousing ideas, as well as experimenting with numerous adhesive removal techniques. The main requirement for the adhesive removal was to be able to lift a range of adhesives, at various stages of degradation on differing primary supports allowing for the safe and quick removal of carrier and adhesive for the majority of the 2500 prints. It was decided quite early on during the survey that a poultice would work best for such a task. A poultice is a swelling agent commonly made with a viscous substance used to slowly and controllably release moisture. This would permit a number of objects to be treated simultaneously and, if the correct poultice method was adopted, to remove an adhesive easily and equally – such a technique would not only be beneficial for the wellbeing of the prints, but would also be time and cost effective.
I began my experimentation with the Albertina poultice, a ready for use amylase poultice that removes un-swellable starch pastes. I was sent a sample kit, which comprised of two interleaving silk tissue papers, an amylase poultice, and a small piece of blotter. I experimented with this system on a variety of prints from the collection, however whilst the poultice worked wonderfully on some adhesives and carriers (presumably starch based) the poultice failed on others. Because of this I believed that despite the Albertina poultice working well on certain adhesives, and with the added benefit of reusability (the Albertina poultice can be stored and reused for at least 12 months) it was not a suitable option considering the varied adhesives present within the collection.
Next, I experimented with high viscosity carboxymethyl cellulose sodium salt poultice strips, a method devised at the Book and Paper Conservation Studio at the University of Dundee. To be efficient and economical the CMC is wrapped in Japanese tissue to create individual poultice strips that are then placed directly onto the carrier of the adhesive and left to take action. I discovered that to easily remove the adhesive and carrier the poultice strip only needed to be in place for about 20 minutes and thereafter the adhesive/carrier could be gently lifted and removed. This particular poultice worked on a variety of tape and adhesives and the reusable strips were easy to handle and manipulate according to shape and size of the adhesive layer. So far the poultice has been successful on a range of tapes and adhesives including starch based adhesives, animal glue, and masking and glassine tape.
And so, there you have it, the Carboxymethyl Cellulose strips created perfect and painless poulticing – a swift operation, if I do say so myself…
Post by Samantha Cawson, Conservation Intern